In order to connect, the version of Design Studio and Content
Transformation Engine (CTE) must be identical. You can determine the version
from the server log. Use the administration interface to view the log. The
first message is the CTE software version. For the Design Studio, verify the
version from the Help —> About� tab.

In order to resolve the issue, apply the full patch upgrade. In order
to apply the patch you need one of these: